I stopped using hg fetch
to pull and merge in another head for a Mercurial repository because I like to make the commit message say what is merging with what. Furthermore, I am moving from "merge repo1 -> repo2" to a more specific "merge head1guid -> head2guid" format.
How can I automate this so I don't have to list the heads with hg heads
then copy and paste the guids for the two changesets into my commit message?